[FFmpeg-devel] [PATCH] Long-term prediction for ALS

Thilo Borgmann thilo.borgmann
Thu Nov 12 19:12:52 CET 2009


Michael Niedermayer schrieb:
> On Thu, Nov 12, 2009 at 10:51:05AM -0500, Ronald S. Bultje wrote:
>> Hi,
>>
>> On Thu, Nov 12, 2009 at 10:45 AM, Stefano Sabatini
>> <stefano.sabatini-lala at poste.it> wrote:
>>> On date Thursday 2009-11-12 16:37:04 +0100, Thilo Borgmann encoded:
>>>> +    // set lag value for long-term prediction
>>>> +    if      (avctx->sample_rate >= 192000)
>>>> +        ctx->ltp_lag_length = 10;
>>>> +    else if (avctx->sample_rate >=  96000)
>>>> +        ctx->ltp_lag_length = 9;
>>>> +    else
>>>> +        ctx->ltp_lag_length = 8;
>>>> +
>>> Slightly simpler:
>>>
>>> ctx->ltp_lag_length = avctx->sample_rate >= 192000 ? 10 :
>>>                      avctx->sample_rate >=  96000 ?  9 : 8;
>> ltp_lag_length = 8 + samplerate >= 96000 + samplerate >= 192000;
>> (might need brackets).
> 
> ltp_lag_length= 8 + FFMIN(samplerate/96000, 2);
> 
> if one wants the most compact source ...

Revision++

-Thilo
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